A 3.2 million-year-old fossil bone support Australopithecus afarensis was recovered from Hadar, Ethiopia, according to a Journal Science report on Friday, February 11, 2011. The fossil supports humanlike bipedalism in Lucy‘s species.

The fossilized foot bone shows that 3.2 million years ago, humans walked bipedally with a modern human-like foot, as concluded by the Journal Science. According to Carol Ward of the University of Missouri, the fourth metatarsal fossil, or midfoot bone, shows that there was a permanently arched foot in the species Australopithecus afarensis. Ward is one of the authors of the Journal Science research that include William Kimbel and Donald Johanson, of Arizona State University‘s Institute of Human Origins.

The recent findings might help resolve a long-standing argument among paleoanthropologists who believes that A. afarensis walked like modern humans and those who believe that Lucy species practiced a form of locomotion intermediate between the quadrupedal tree-climbing of chimpanzees and human terrestrial bipedalism.

The fossil was recovered in Hadar locality 333, also known as the “First Family Site,” considered as the richest source of A. afarensis fossils in eastern Africa. There are about 250 known specimens, representing at least 17 individuals.

Humans are unique primates with two arches in their feet, longitudinal and transverse, with midfoot bones and supported by muscles in the sole of the foot. The arches is used to leverage when the foot is lifted up and as shock absorption when the foot touches the ground while walking or jumping.

Ape do not have permanent arches on their feet but are more flexible than human feet with a highly mobile large toe that they can use in climbing and grasping in the trees.